Within the field there are two primary types of load securing devices; the first being a ratchet style tensioning device and the second being cam locking device. There are many applications for both of these devices and they are widely used throughout many industries.
In the case of the ratchet tensioning device, there are a number of drawbacks, the first being in the complexity of the device and its use. The ratchet and webbing system is made of many movable parts that are not immediately clear how to operate or actuate. This can lead to confusion and outright inoperability of the device depending on the users prior knowledge. The routing of the webbing, the release mechanism, and the actuation direction are all things that are not intuitive for people to operate.
Another negative aspect of the ratchet is the complexity of the design. The system has many parts including but not limited to; attachment hardware, springs and multiple steel stampings. All of these things increase to time and complexity of assembly as well as increase to chances that a part or assembly could fail.
The cam-locking device solves the immediate drawbacks of the ratchet device buy simplifying the design complexity. The total number of parts is less than one half of that of a ratchet style device. With the simplification of design comes the clearer easy to use function of the design. However the cam style tie down has its own major flaws. The first being that the device can only apply a tension that is slightly less than the input force from the user, considering the loss of friction.
It has been considered to use a block and tackle in combination with a cam style tie-down as in US patent application 2011/0209314. This would increase the tension on the load while decreasing the input force required from the user. Of course this design is not without its drawbacks. The multiple loops of webbing can get twisted or convoluted thereby eliminating the benefit of the mechanical advantage. Additionally the multiple loops of webbing must be in a relatively straight line between the load attachment and the cam lock in order for the mechanical advantage not to be overcome with friction in the system. A straight line for the entire length of the tie down is a rare occurrence as many times the attachment point is not conveniently located or the strapping is fed over the load before being tightened.
Significant advantages would be realized by an improved belt tensioning system that would be simple to use, allow an increase in mechanical advantage, and adaptable to work in many situations.